Getting the best out of brassica products

With a focus on insecticides, biostimulants, fungicides, and nutrition, Hutchinsons’ brassica demonstration day was held at Old Leake, Boston, on October 9th in conjunction with the Allium & Brassica Centre.

The aim of the plots is to refine understanding of new products that are near-market, explained Peter Waldock, Hutchinsons technical support for vegetables. “Many of the new products coming on the market are predominantly protectant rather than having a knock-down effect, so applications have to be better targeted to optimise efficacy,” said Peter. “Our trials are exploring maximising efficacy in kale and Brussels sprouts, and the knowledge gained can then be related to all brassica crops.”

With the loss of Cruiser (Thiomethoxam) for aphid control, growers are likely to become more reliant on foliar sprays, so plots were set up to look at products both on their own and in combinations. These plots were treated with Tracer (spinosad) for cabbage root fly control, although it has no effect on aphids or white fly, noted Peter.

The first insecticide application took place on July 3rd, followed by another ten days later. The new insecticide Isoclast was included in the trials and was reported to be “looking very good”. Peter said: “This product will have minimal impact on beneficials so will fit well within IPM programs. Additionally, it has systemic and translaminar properties as well as having a very fast feeding cessation and should reduce the risk of virus spread. It will also remain active in the plant for 10 to 14 days.

“All the treatments we used have showed positive results for aphid control. However, to get the best results from Movento (spirotetramat) it should be applied ahead of aphid populations building to give the best control,” he cautioned, adding that it was the best insecticide in the trial against white fly.


While the warm summer of 2018 proved favourable to aphids, there was not a lot of leaf disease pressure, making it difficult to distinguish differences between products. “Brussels sprouts are susceptible to light leaf spot and ring-rot, while kale is more likely to be affected by powdery mildew.

“If you can get an early application of Signum (Boscalid/pyraclostrobin) on at around four weeks after planting, you get the benefits of its protectant properties for longer than the recognised 10 to 14 days,” said Peter.

However, he also warned that with the new labels this year for Amistar Top and Amistar regarding the grams active of azoxystrobin (500 gai/ha) per hectare per year, and a restriction on the Amistar Top label for difenoconazole (250 gai/ha), growers need to ensure they do not breach the labels restrictions when using these products.


Moving on to talk about bio-stimulants, he said: “Although the dry year has been a challenge, we found that reducing N in the base and then topping up with foliar applied nitrogen was effective. Also, although historically there has been concern with using foliar nitrogen applications as leaf scorch can be an issue, this does not seem to be an issue with the new foliar products we’ve tested”.

“One of the further benefits of good nutrition programmes is that it enhances plant health, creating the right environment for the plant to maximise its own defences.”

Cover crops

There was also an area dedicated to varietal choice for cover crops. “Choosing the right varieties to grow an effective cover crop is crucial,” said Dick Neale, Hutchinsons technical manager. “The soil in the area is good quality silt loam rich in nutrients but low in organic matter, and it needs care to maintain good structure.”

Several mixes had been drilled on August 3rd, but vetch and berseem clover had not established well, partly because the soil had run together compromising their emergence, explained Dick. However, linseed had got away nicely, as had radish and phacelia. “You want enough biomass and root matter to make a difference to soil health, but the needs of vegetable farmers are different from arable growers.

Whereas arable farmers may want and can cope with strong above ground growth and roots which are going to penetrate and break open the soil, vegetable growers on this sort of soil are looking for a manageable amount of top growth with finer roots so as not to interfere with more complex planting and harvesting procedures.”

Linseed also performed well on the site. When it was on its own it had tillered well, whereas when it a mix it had grown taller because of the competition with the other seeds. “A suggestion would be to look at growing rye, linseed and berseem clover, as it will fix N and be relatively easy to strip-till and plant vegetables directly into it,” said Dick.

New roller

On-show was a recent innovation by Cousins of Emneth, a crimper roller with helical blades to roll, break and bruise cover crops ahead of the drill. When rolled down in the direction of planting, the cover crop can form a dense weed suppressing mat on the soil surface while allowing successful crop establishment, explained managing director Laura Cousins

In addition, the blades are ‘blunt’ as ‘sharp’ blades can cut through the cover crop and into the soil, dislodging residue and increasing weed seed germination. “The blades are spiral, so this helps prevent vibrations and keeps the machine moving smoothly,” she said. “As only a small portion of the twisted blade is in contact with the ground at any time, the full pressure of the roller is applied intensely, optimising the breaking and crimping of stems to aid cover crop desiccation.” A front mounting allows rolling and drilling to be done in a single pass, she added.